An Investigation on the mineralogical and chemical characterization, pore structure, chemical shrinkage
and pozzolanic activity of commercially produced rice husk ashes (RHA 1 and 2) and a control silica fume (SF)
are presented in this paper. RHA possesses high silica content like silica fume which is used as supplementary
cementitious materials (SCM) in the production of concrete. There is a need for an alternative to silica fume in
the production of concrete because of its high demand and relatively high cost.
The mineralogical composition of RHA 1 and 2 show high silica content of 77% and 84% respectively which is
close to the silica content (˃80%) of class 2 silica fume. The oxides of Ca are 3.53% and 7.68% while Al is 1.19%
and 1.29% for RHA 1 and 2 respectively which suggest that RHA is a low Ca+2 content binder. The results of
chemical shrinkage of RHA 1, 2 and SF are 0.42 mL/g, 0.52 mL/g and 0.11 mL/g after 500 hrs of hydration. This
indicates that RHA 2 has the highest reactivity (hydration) with water due to its highest Ca+2 content
